Aglaophamus malmgreni

Aglaophamus malmgreni (Théel, 1879)

Figures 2, 4

Nephthys malmgreni Théel, 1879: 26, pl. I, fig. 17, pl. II, fig. 17; Marenzeller 1904: 304–308; Heinen 1911: 29, fig. 8, map 2 (partim); Augener 1912: 206; not Treadwell 1914: 192; Fauvel 1914: 196; Fauvel 1923: 371, fig. 145K; Ditlevsen 1937: 19.

Nephthys longisetosa [misspelling of longosetosa] Malmgren 1865: 106, pl. XII, fig. 20; Malmgren 1867: 19 (not Nephtys longosetosa Örsted, 1843).

Nephthys atlantica Hansen, 1878: 4, pl. III, figs. 1 and 2; Hansen 1882: 31, pl. 4, figs. 1–4.

Nephthys grubei McIntosh, 1900a: 33; McIntosh 1908: 33, pl. LVII, figs. 13 and 14; pl. LXVII, fig. 1; pl. LXXVI, figs. 9 and 9A.

Nephtys malmgreni Uschakov 1955: 217, fig. 69E.

Nephtys (Aglaophamus) malmgreni Berkeley and Berkeley 1956: 235; Day 1967: 343, fig. 15.1N –O.

Aglaophamus malmgreni Pettibone 1956: 557; Fauchald 1963: 17, figs. 1F, 2F, 3G, 4, 8A, 9, table 1; Pettibone 1963: 191, fig. 48B; Wolff 1968: 6, fig. 13; Hartmann-Schröder 1971: 224; Hartmann-Schröder 1974: 205, fig. 26 (partim); Jirkov 1989: 73, fig. 15.2 and 15.3; Kirkegaard 1992: 326, fig. 158; Hartmann-Schröder 1996: 216; Dnestrovskaya and Jirkov 2001: 187,1 text-fig.

Aglaophamus malmgreni ? Imajima 1970: 116, 120; Campoy 1982: 507; Imajima and Takeda 1985: 68, fig. 6A–N; Laborda 2004: 412, fig. 151B.

Nephtys longisetosa Malmgren 1865: 106, pl. 12, fig. 20 (not Ørsted 1842).

Type locality. Off Novaya Zemlya.

Material examined. Arctic Ocean. Svalbard, Billefjord: coll. RV Jan Mayen, 78º37.764’N, 16º25.359’E, 38 m, grab, Sep 2003, 1 incomplete spm (DBUA 01043); Wijdefjord: coll. RV Jan Mayen, 79º07.623’N, 16º02.743’E, 217 m, grab, Sep 2003, 1 complete spm (DBUA 01043-02) and 1 incomplete spm (MB36000138); Spitsbergen: 1 complete spm (NHM 1865.9.23.11 as N. longosetosa).

Atlantic Ocean. Faroe Channel: Knight-Errant Faroe Channel expedition, 60º3’N, 5º51’W, 540 fms, Aug 1880, 1 complete spm (NHM 1921.5.1.832, holotype of N. grubei). Off Norway: TTR16 cruise, coll. RV Prof. Logachev, 64º40.014’N, 5º17.411’E, 735 m, grab, Jun 2006, 1 incomplete spm (MB36000133); Portugal, off Setúbal: Challenger expedition, 1 incomplete spm in poor condition (NHM 1885.12.1.129).

Description. Examined specimens up to 52 mm long for up to 77 chaetigers. See Fig. 2 for length and width measurements. Body slightly wider anteriorly, gradually tapering from middle region to pygidium. Poor dorsal delineation between anterior segments. Colour in ethanol pink with darker areas in first segments and near bases of parapodia; prostomium with two darker areas near the bases of antennae; chaetae and aciculae amber. Eyes not visible. Pharynx distal region with 10 pairs of terminal bifid papillae, separated by simple conical dorsal and ventral papilla; middorsal and midventral papilla absent; subdistal region with 22 rows of 2–18 subterminal papillae, extending over 1/2 length of pharynx, proximal papillae close together and sometimes arranged in pairs, larger papillae ventrally crenulated (Fig. 4A–B); proximal region smooth. Jaws conical (Fig. 4C). Prostomium subpentagonal, anterior margin slightly concave, tapered, forming membrane between antennae; posterior margin V-shaped, extending over first chaetiger (Fig. 4A); antennae and palps conical, palps slightly longer than antennae (Fig. 2C), inserted ventrolaterally on anterior part of prostomium. Nuchal organs rounded. Parapodia biramous; interramal space “U-shaped” anterioly and medially, “Vshaped” posteriorly, with small ciliated patches. Parapodia of chaetiger 1 equal in size to subsequent ones, anteriorly directed, parallel to prostomium; notopodial acicular lobes conical, prechaetal lamellae rudimentary, postchaetal lamellae poorly developed, rounded; neuropodium with pre- and postchaetal lamellae forming a cylinder covering acicular lobes; dorsal cirri very small, rounded (Fig. 2D); ventral cirri conical to digitiform with broad bases and tapering distally. Acicular lobes of following parapodia acutely pointed; pre- and postchaetal lamellae of both rami well developed but not extending beyond acicular lobes, becoming less developed more posteriorly and rudimentary in posteriormost parapodia; notopodial prechaetal lamellae rounded, postchaetal lamellae of median parapodia bilobed with dorsal part directed dorsally, rounded on other parapodia but always directed dorsally; neuropodial pre- and postchaetal lamellae conical to rounded; dorsal and ventral cirri conical (Fig. 4D–G). Branchiae involute, cirriform, lightly ciliated, on chaetigers 11–13 to 36–41, always well developed; occupy all interramal space when fully developed. Chaetae of three kinds: barred chaetae in preacicular position (Fig. 4H), spinulated chaetae in postacicular position (Fig. 4I), and capillary chaetae in neuropodia of chaetiger 1. One acicula with curved tip per ramus (Fig. 4J).

Remarks. Aglaophamus malmgreni is herein included in the South European fauna, based on the scarce records from the Mediterranean Sea and the western coasts of Spain and Portugal (Fauvel 1923; Campoy 1982; Laborda 2004). Unfortunately there were no specimens available to confirm these records. The only material examined was a single specimen from Portugal, in very poor condition, from which the identity could not be confirmed. Fauvel (1923) and Campoy (1982) provided descriptions for southern Europe specimens that agree with A. malmgreni, although Campoy did not examine specimens of this species. On the other hand, Laborda (2004) described notopodial postchaetal lamellae as rounded (only slightly bilobed in anteriormost parapodia) instead of distinctly bilobed in median parapodia. The same feature was described by Imajima and Takeda (1985) for Japanese specimens, although, considering the very different geographical regions, the Japanese specimens are not likely to be conspecific with the southern European ones. The material examined and most literature references suggest a circumpolar distribution for A. malmgreni. We thus believe that the South European records require confirmation and must be considered with caution until more specimens from this region become available for further examination.

In the specimens examined the pharynx has 14 rows of 11–18 papillae intercalated with 8 rows of only 2 or 3 papillae, adding to a total of 22 rows of 2–18 papillae. Those shorter rows seem to have been overlooked in previous studies. Pettibone (1956) noticed the presence of “some additional scattered papillae more distally” in the pharynx, but did not consider them as additional rows of papillae. Thus, the original description of A. malmgreni is herein emended to include 22 rows of 2–18 pharynx papillae instead of 14 rows of 10–18 papillae as stated in previous descriptions.

Distribution. Arctic Ocean (Svalbard, Barents Sea, Kara Sea, Laptev Sea); Atlantic Ocean (Norway, Sweden, North Sea; Greenland, Canada, NE coast of North America); Pacific Ocean (Bering Sea, Sea of Okhotsk, N Japan Sea) (Hartman 1938; Pettibone 1956; Imajima & Takeda 1985; Dnestrovskaya & Jirkov 2001; Laborda 2004). There are further reports of this species from NW Spain, Portugal and the Mediterranean Sea (Fauvel 1923; Pettibone 1956; Campoy 1982; Laborda 2004), but these records require confirmation.

Habitat. Muddy bottoms, 22–3820 m depth (Dnestrovskaya & Jirkov 2001)